Transcriptomics and metabolomics profiling reveal that molecular mechanism of jasmonic acid regulating adventitious root genesis in Toxicodendron succedaneum (L.) Kuntze

Adventitious root (AR) development is critical for plant reproduction. Toxicodendron succedaneum (L.) Kuntze is an important economic species. In the process of establishing a regeneration system for T. succedaneum, it was found that using axillary buds (TSE) as explants resulted in a rooting rate of 1 %. However, when stem segments from rooted tissue culture seedlings (TSW) were inoculated into the same rooting medium, the rooting rate increased to 100 %. In order to explore the rooting differences between TSE and TSW, transcriptome, metabolome, and phytohormones measurements were conducted. Transcriptomics results show that the differentially expressed genes (DEGs) are mainly enriched in valine, leucine, and isoleucine degradation, plant hormone signal transduction, and flavonoid and flavonol biosynthesis pathway. Metabolomics show that metabolites such as lipids, flavonoids, and organic acids exhibit differential accumulation between TSE and TSW. Integrated transcriptomic and metabolomic analysis revealed that at 12 h of culture, the expression levels of key genes (DAD1, AOS, LOX, OPR and MYC2) in the jasmonic acid (JA) biosynthesis pathway were significantly lower in TSW than in TSE. Further analysis of hormonal dynamics confirmed that JA levels were consistently significantly higher in TSE than in TSW. To verify the regulatory role of JA in roots, exogenous JA and the JA biosynthesis inhibitor diethylamine (DIECA) were added to the medium. The results showed that different concentrations of JA inhibited the rooting rate, root number, root length, and lateral root development in TSW. In contrast, the addition of 100 µM DIECA significantly promoted lateral root formation in TSW. Furthermore, the same DIECA treatment also effectively enhanced rooting in TSE, offering fresh proof of the critical function of JA signaling in controlling the rooting process in T. succedaneum.